| 摘要 |
PURPOSE:To recover the normal operation after the specified time from the disturbance caused by noises by introducing interlock signals between ring counters which control a plurality of mutually connected current-control type frequency converter. CONSTITUTION:A DC power supply 11 drives an AC motor 18 through multiple- current type inverters 14 and 15. The pulses, which are generated by an oscillator 20 depending on a value specified by a frequency standard 19, are counted by ring counters 22 and 23, thereby thyristors in the inverters 14 and 15 are controlled and hence the speed of the motor 18 is controlled. Interlock signals S8 and S9 are introduced between the ring counters 22 and 23, so that the signal of one ring counter is input to the other ring counter at least once during the one cycle of the output frequency. Therefore, even the ring counters operate erroneously by the incoming noises, it is possible to recover the normal operation after the specified time, and reliability can be enhanced. |
